RU2428258C2 - Method of dressing coal slime - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to dressing of minerals, particularly, to dressing coal slime. Proposed method comprises slime thickening, slime dressing and dewatering of separation products. Slime thickened in centrifugal field, dewatered sediment and centrifuge effluent are separated. Dewatered sediment is added to concentrate while centrifuge centrate is thickened and dewatered. Then, depending upon required ash content of commercial products, for example, not over 10%, it is added to commercial product produced in coal dressing, crude slime or dressing wastes.

EFFECT: higher efficiency and simplified process.

2 cl, 1 dwg, 2 tbl

Description

The invention relates to the enrichment of minerals, in particular to the enrichment of coal sludge.

Known methods for the enrichment of coal sludge, including the classification, thickening, actually enrichment and dewatering of sludge and products of their separation, while differences in the properties of the processed sludge and tasks arising in the treatment of sludge water, lead to the fact that the number of technological operations varies and the scheme for processing slurry waters are built in different ways. In the known method [1] the actual enrichment of sludge with a high content of small classes (less than 0.5 mm) is most effectively carried out by flotation. When using flotation, there is a fairly effective separation of sludge particles by density and the ash content associated with it. However, significant disadvantages of flotation are the high cost of marketable products due to the use of expensive flotation agents, as well as environmental pollution by these reagents.

The closest analogue of this invention to the technical nature and the achieved result is a method [2] for sludge enrichment, including sludge thickening, preparation of pulp for flotation by hydroseparation with treatment with flotation reagents and separation of dehydrated rock, flotation of the hydrogeration centrifuge after removal of the solid phase and return of flotation waste for hydroseparation [2].

In the preparation of the pulp by hydroseparation, the process of its enrichment occurs with the release of the centrate and dehydrated rock, which is removed into the hopper. The concentrate solid fraction is partially isolated from the centrate in a dewatering apparatus (disk vacuum filter) and is seated to the concentrate, and the rest of the centrate is sent to flotation. Flotation waste after thickening is returned to the hydroseparation for additional enrichment.

The disadvantage of this method is the presence in the circuit of circulating flows, complicating the process of enrichment of sludge and reducing its effectiveness. In preparation for flotation, the treatment of the entire pulp, including that which then does not go to flotation, makes the process more expensive due to the irrational use of expensive and negatively affecting the ecology of flotation reagents.

The basis of the invention is to develop a method for enriching coal sludge by separating dehydrated sludge and a centrate from the sludge in a centrifugal field, while the dehydrated sludge is added to the concentrate, and the centrate is thickened, dehydrated and depending on the required ash content of commercial products, for example, not more than 10%, sent to the additive to the industrial product obtained by coal enrichment, to non-enriched sludge or waste enrichment, and separation in a centrifugal field is carried out in a filtering screw centrifuge, which uet improve the efficiency of enrichment, simplify the process and reduce costs, and reduce the negative impact on the environment.

The problem is solved in that a method is proposed for enriching coal sludge, including thickening the sludge, enriching it in a centrifugal field with the release of dehydrated sludge and a centrate, while the dehydrated sludge is added to the concentrate, and the centrate is thickened, dehydrated and depending on the required ash content of commercial products, for example not more than 10%, sent to the additive to the intermediate product obtained by coal enrichment, to unreinforced sludge or to waste enrichment, and separation in a centrifugal field is carried out in a filtering screw centri Uge.

In the proposed technical solution, separation in a centrifugal field is characterized in that the slurry particles are separated by size, and not by density.

The advantage of separation in a filtering screw centrifuge is that fine particles with an ash content higher than the ash content of the larger particles remaining in the sediment are removed through centrifugal forces through the slot hole of the rotor. As a result, the waste product is not dehydrated, which is the case in the hydroseparator, but the target product with a moisture content of 16-20%, which, bypassing drying, can sit down to the concentrate so that the total humidity satisfies the requirements for commercial products.

When dehydrating a concentrate product with a fineness of the main fraction (component of at least 80%) of 50-200 microns in other dewatering devices, except for sedimentation-filtering centrifuges such as decanter, humidity is 6-10% higher.

In the proposed method, the centrate, dehydrated after thickening, is the final product. The absence of the operation of enrichment of the centrate with flotation and circulation of separation products greatly simplifies and reduces the operational costs of the enrichment process. The absence of flotation reagents simplifies, reduces the cost of the process and reduces the negative impact on the environment.

In the proposed technical solution, the particle size class with the required ash content is determined by the sieve composition of the sludge sent for centrifugation, and size separation is carried out, preliminarily determining the size limit of particles carried to the centrate. With effective separation and optimal solid content of 400-500 g / l, 80-90% of particles of this class are transferred to the centrate.

The method is as follows. Slurry water (drawing) after thickening (1) is sent to a screw filter centrifuge (2). The main separation process occurs in a centrifugal field in the pressure filtration zone, created due to the difference in rotor and screw speeds. Particles with high ash content, particle size less than the upper limit of the fineness of the fine fraction to be removed in the centrate, are removed with the centrate during filtration, and low-ash larger particles remain in the sediment.

The width of the slit of the filtering rotor should be 4 times the theoretical upper size limit (determined by the sieve composition) of the particles, which should go into the centrate with a probability of 75-80%, which ensures the most efficient separation. If the gap width is greater than the specified value, the concentrate ash particles may be entrained into the centrate, which leads to an undesirable loss of combustible mass; when exceeded less than 4 times, fine particles are retained in the sediment and increase its ash content.

The rotor slots are formed by grid-irons having a trapezoidal cross section with a taper angle of less than 30 ° and a larger base to height ratio of less than 0.5, which facilitates the passage of entrained particles and reduces the risk of particles clogging the gap.

With a centrifuge content of 400-500 g / l solid in the feed, the most efficient ablation of fine particles occurs and their extraction into the centrate can reach 80-85%. Sediment from the surface of the rotor is transported by a screw, gets to the appropriate conveyor and sent to the additive to the concentrate. The centrate from the centrifuge enters the thickener (3).

The thickener discharge is directed to recycled water supply, the condensed product is sent to dehydration (4), and then to an additive to the industrial product, non-enriched sludge or enrichment waste, depending on the ash content and purpose of the products.

Example. Sludge waters with a solids content of 50-60 g / l are thickened in a thickener to a density of 400-500 g / l. The sieve composition of the condensed product with ash content (centrifuge feed) is shown in Table 1.

Table 1 Screening composition of the filter screw centrifuge Nutrition (A = 15.3%; solids content C = 451.4 g / l) Class mm Yield,% Ash content, A,% Total top Y% BUT, % > 0.5 5.1 7.0 5.10 7.00 0.315-0.5 8.5 7.8 13.60 7.50 0.2-0.315 13,2 8.4 26.80 7.94 0.125-0.2 14.8 9,4 41.60 8.46 0,063-0,125 24.2 10.9 65.80 9.36 0-0.063 34.2 26.7 100.00 15.29 Total 100.0 15.29

table 2 The results of enrichment in a filtering screw centrifuge Sludge - concentrate Class mm Yield,% Ash content, A,% Total top Y% BUT, % > 0.5 8.8 7.0 8.8 7.0 0.315-0.5 23.5 7.5 32.3 7.36 0.2-0.315 26.7 8.3 59.0 7.79 0.125-0.2 25.9 9.5 84.9 8.31 0,063-0,125 8.6 10.6 93.5 8.52 0-0.063 6.5 24.1 100.0 9.53 Total 100.0 9.5 Fugat - industrial product Class mm Yield,% Ash content, A,% Total top Y% A% > 0.5 0,0 0,0 0,0 0,0 0.315-0.5 0.7 8.1 0.7 8.10 0.2-0.315 6.2 9.9 6.9 9.72 0.125-0.2 10.6 12,4 17.5 11.34 0,063-0,125 20.1 22.8 37.5 17.47 0-0.063 62,4 28.7 100.0 24.48 Total 100.0 24.5

Obviously, based on the sieve composition of the food, in order to obtain the required ash content of coke concentrate of not more than 10%, separation should be carried out on a particle size of 0.063 microns. The size of the slit is 0.25 mm. For a given solid content in the diet (Table 1), the following separation results were obtained (Table 2): the precipitate yield in a centrifuge Yoc. = 61.4%, with ash content A = 9.5% and humidity W ^r = 16.4 %; yield of centrate Yfug. = 38.6%, with ash content A = 24.48% and solid content C = 224.5 g / l. In this example, the centrate after thickening and dehydration is sent to an additive to the industrial product obtained by coal enrichment.

Information sources

1. Recycling water supply to coal processing plants. M .: Nedra, 1980.P.136.

2. A.S. No. 1346250, cl. B03B 7/00, 1987.

Claims (2)

1. A method of sludge enrichment, including sludge thickening, their enrichment and dehydration of separation products, characterized in that after the sludge is condensed from the sludge in a centrifugal field, a dehydrated sludge and a centrate are isolated, while the dehydrated sludge is added to the concentrate, and the centrate is thickened, dehydrated and depending of the required ash content of marketable products, for example, not more than 10%, is sent to an additive to the industrial product obtained by coal enrichment, to non-enriched sludge or to enrichment waste. 2. The method according to claim 1, characterized in that the separation in a centrifugal field is carried out in a filtering screw centrifuge.

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